/*
 * Copyright (C) 2010 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.moshi;

/**
 * Lexical scoping elements within a JSON reader or writer.
 */
final class JsonScope {
    private JsonScope() {
    }

    /**
     * An array with no elements requires no separators or newlines before it is closed.
     */
    static final int EMPTY_ARRAY = 1;

    /**
     * A array with at least one value requires a comma and newline before the next element.
     */
    static final int NONEMPTY_ARRAY = 2;

    /**
     * An object with no name/value pairs requires no separators or newlines before it is closed.
     */
    static final int EMPTY_OBJECT = 3;

    /**
     * An object whose most recent element is a key. The next element must be a value.
     */
    static final int DANGLING_NAME = 4;

    /**
     * An object with at least one name/value pair requires a separator before the next element.
     */
    static final int NONEMPTY_OBJECT = 5;

    /**
     * No object or array has been started.
     */
    static final int EMPTY_DOCUMENT = 6;

    /**
     * A document with at an array or object.
     */
    static final int NONEMPTY_DOCUMENT = 7;

    /**
     * A document that's been closed and cannot be accessed.
     */
    static final int CLOSED = 8;

    /**
     * Sits above the actual state to indicate that a value is currently being streamed in.
     */
    static final int STREAMING_VALUE = 9;

    /**
     * Renders the path in a JSON document to a string. The {@code pathNames} and {@code pathIndices}
     * parameters corresponds directly to stack: At indices where the stack contains an object
     * (EMPTY_OBJECT, DANGLING_NAME or NONEMPTY_OBJECT), pathNames contains the name at this scope.
     * Where it contains an array (EMPTY_ARRAY, NONEMPTY_ARRAY) pathIndices contains the current index
     * in that array. Otherwise the value is undefined, and we take advantage of that by incrementing
     * pathIndices when doing so isn't useful.
     */
    static String getPath(int stackSize, int[] stack, String[] pathNames, int[] pathIndices) {
        StringBuilder result = new StringBuilder().append('$');
        for (int i = 0; i < stackSize; i++) {
            switch (stack[i]) {
                case EMPTY_ARRAY:
                case NONEMPTY_ARRAY:
                    result.append('[').append(pathIndices[i]).append(']');
                    break;

                case EMPTY_OBJECT:
                case DANGLING_NAME:
                case NONEMPTY_OBJECT:
                    result.append('.');
                    if (pathNames[i] != null) {
                        result.append(pathNames[i]);
                    }
                    break;

                case NONEMPTY_DOCUMENT:
                case EMPTY_DOCUMENT:
                case CLOSED:
                    break;
            }
        }
        return result.toString();
    }
}
